1. Technical Field of the Invention
This invention generally relates to a container useful for storing and transporting food and specifically, to a container including a base portion and a lid portion formed to include a double seal which adjusts for variations in the size of the base portion or the lid portion.
2. Description of the Background Art
Convenience is essential for modem food packaging. Packaging which requires care or special attention will normally fail in the market while it seems that products succeed only when they are not only low in cost, but also extremely simple and easy to use. Even though the microwave oven has made cooking, or more specifically heating, of foods far quicker and more convenient, still simpler, more convenient and lower cost containers are needed. In addition, more establishments have recently begun offering foods on a carry-out basis which are substantially ready for consumption but are meant to be taken home and, possibly, reheated in the microwave oven by the consumer. Containers for this market should be attractive, low in cost, easy to seal, easy to open, easy to reseal, stackable and storable in the lowest possible volume. Most importantly, they must be low in cost and easy for customers to use.
One significant feature important to consumers with regard to containers is providing an appropriate seal between the lid of the container and the base. U.S. Pat. No. 3,964,635, issued to Ludder discloses a recess, rim-locking container closure for attachment to a wide-mouth container. The lid includes an annular portion fitting over a portion of the container. Specifically, the container is required to include a curled rim or bead surrounding the open mouth thereof. The rim of the container does not extend downwardly and outwardly below the lower extent of the lid which requires the lid and base to be molded to very close tolerances. Moreover, the lid is formed in a "female mold" and clearly does not include formation by a "male mold" which is generally more efficient.
U.S. Pat. No. 3,805,991 to Cheladze et al. is also directed to a lid having a rim structure which includes an annular, channel-shaped region for engaging a rim of a container. However, again the container does not include a matingly shaped rim to engage the annular sealing region of the lid to provide a superior "dual" sealing area and to allow for variations in the size of the lid or container while still providing an adequate seal. Additional U.S. Pat. Nos. to Negoro (3,065,875); Holt (3,977,563); Stubbs, Jr. (4,037,748); Letica (4,293,080); and Anderson (4,380,304) each disclose examples of snap-on lids and containers. However, each of these lids include substantial undercuts required to provide the seal between the lid and the container, but which also increase the amount of force required to open and close the containers.
Attempts have been made to relax the undercuts needed to produce a seal between the container and the lid, such as U.S. Pat. Nos. to Collie (3,351,227); Fotos (3,362,575); and Davis (3,779,418). Each of these patents disclose lids having more relaxed undercuts, but in many cases, if the undercuts are relaxed without any modification of the container, an adequate seal is not provided. This can be especially detrimental for containers used for transporting and storing food products. Many food products release considerable amounts of steam during cooking so a strong seal between the lid and the container is very important to guard against leakage of hot contents onto the hands of the person removing the container from the oven.
In addition to the importance of a lidded container providing a reliable seal, the container and lid should also be conveniently manipulated to serve many purposes. Containers have been designed wherein the base or container is insertable into a portion of the lid to provide a stacking feature. U.S. Pat. Nos. to Bird (3,912,118); Holt (4,047,329); Fotos (3,362,575); Holley (3,246,786); and Buonauro (3,089,605) each disclose a base to lid stacking arrangement. However, each of the containers disclosed in these patents do not include a substantially fiat base, and all but the '329 patent include downwardly extending rims to raise the base of the container off of the ground. Such an arrangement can cause instability between the base and the lid because only a limited portion of the base is in actual contact with the lid.
Another useful feature for a lidded container are audible engaging members which provide the user with a positive indication when the lid and base are in sealing engagement. U.S. Pat. No. 3,452,896 to Elliot discloses a container which audibly indicates of when the lid is in place on the container. Further, U.S. Pat. No. 3,912,118 to Bird discloses a container lid having holes provided in the lid to release steam from the interior of the container wherein the holes are provided in bosses projecting into the container so that the lid may also be used as a server for the food without permitting grease to run through the holes. These patents do not, however, disclose containers with a self compensating double seal.
An additional feature which is useful for any mass produced and stored container are denesting lugs. U.S. Pat. No. 3,615,039 to Ward illustrates denesting lugs having different configurations on opposing end panels. A number of references disclose interlocking prevention detents of various shapes, e.g. U.S. Pat. Nos. to Edwards (3,091,360); Nascher (3,170,594); Eyles (3,353,707); Bozek (3,632,016); Fletcher (3,721,367); and Mahaffy et al. (3,883,036).
Containers having a lid and a base portion also often include tabs for assisting in the removal of the lid from the base. In some instances, one of the tabs is made longer than the other to ease separation therebetween. U.S. Pat. No. 3,737,093 to Amberg et al. discloses a multi-wall container and package which includes a pair of tab extensions on the container closure and the container body, respectively, wherein the closure tab may be longer than the tab of the container body to permit separation by the user. The container disclosed by Amberg et al. is not directed to a food container having a self compensating double seal.
Therefore, a food container which is attractive, low in cost, easy to seal, easy to open, easy to reseal, stackable and storable in a minimal space is needed. Specifically, a food container including a base and lid portion made from a resilient, low cost material and including an effective seal region is needed to provide mass market food distributors with a cost effective container that also satisfies a consumer's desire for a structurally sound and reliable storing and cooking food container.